Watch applet by Michael Habermann

coreutils/watch.c

@@ -0,0 +1,104 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Mini watch implementation for busybox
+ *
+ * Copyright (C) 2001 by Michael Habermann <mhabermann@gmx.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+
+/* getopt not needed */
+
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include "busybox.h"
+
+extern int watch_main(int argc, char **argv)
+{
+	const char date_argv[2][10] = { "date", "" };
+	const char clrscr[] =
+		"\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n";
+	const int header_len = 40;
+	char header[header_len + 1];
+	int period = 2;
+	char **cargv;
+	int cargc;
+	pid_t pid;
+	int old_stdout;
+	int i;
+
+	if (argc < 2) {
+		show_usage();
+	} else {
+		cargv = argv + 1;
+		cargc = argc - 1;
+
+		/* don't use getopt, because it permutes the arguments */
+		if (argc >= 3 && !strcmp(argv[1], "-n")) {
+			period = strtol(argv[2], NULL, 10);
+			if (period < 1)
+				show_usage();
+			cargv += 2;
+			cargc -= 2;
+		}
+	}
+
+
+	/* create header */
+	snprintf(header, header_len, "Every %ds: ", period);
+	for (i = 0; i < cargc && (strlen(header) + strlen(cargv[i]) < header_len);
+		 i++) {
+		strcat(header, cargv[i]);
+		strcat(header, " ");
+	}
+
+	/* fill with blanks */
+	for (i = strlen(header); i < header_len; i++)
+		header[i] = ' ';
+
+	header[header_len - 1] = '\0';
+
+
+	/* thanks to lye, who showed me how to redirect stdin/stdout */
+	old_stdout = dup(1);
+
+	while (1) {
+		printf("%s%s", clrscr, header);
+		date_main(1, (char **) date_argv);
+		printf("\n");
+
+		pid = vfork();	/* vfork, because of ucLinux */
+		if (pid > 0) {
+			//parent
+			wait(0);
+			sleep(period);
+		} else if (0 == pid) {
+			//child
+			close(1);
+			dup(old_stdout);
+			if (execvp(*cargv, cargv))
+				error_msg_and_die("Couldn't run command\n");
+		} else {
+			error_msg_and_die("Couldn't vfork\n");
+		}
+	}
+
+
+	return EXIT_SUCCESS;
+}

include/applets.h

@@ -532,6 +532,9 @@
 #ifdef CONFIG_VLOCK
 	APPLET(vlock, vlock_main, _BB_DIR_USR_BIN, _BB_SUID_ALWAYS)
 #endif
+#ifdef CONFIG_WATCH
+	APPLET(watch, watch_main, _BB_DIR_BIN, _BB_SUID_NEVER)
+#endif
 #ifdef CONFIG_WATCHDOG
 	APPLET(watchdog, watchdog_main, _BB_DIR_SBIN, _BB_SUID_NEVER)
 #endif

include/usage.h

@@ -2076,6 +2076,18 @@
 	"Options:\n" \
 	"\t-a\tLock all VTs"
 
+#define watch_trivial_usage \
+	"[-n <seconds>] COMMAND..."
+#define watch_full_usage \
+	"Executes a program periodically.\n" \
+	"Options:\n" \
+	"\t-n\tLoop period in seconds - default is 2." 
+#define watch_example_usage \
+	"$ watch date\n" \
+	"Mon Dec 17 10:31:40 GMT 2000\n" \
+	"Mon Dec 17 10:31:42 GMT 2000\n" \
+	"Mon Dec 17 10:31:44 GMT 2000" 
+
 #define watchdog_trivial_usage \
 	"DEV"
 #define watchdog_full_usage \